Commit 088b7052 authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Jens Axboe
Browse files

drbd: fix queue limit setup for discard 



We cannot possibly support SECDISCARD, even if all backend devices would
support it: if our peer is currently unreachable, some instance of the
data may obviously still be recoverable.

We did not set discard_granularity at all.  We don't really care (yet),
we only pass them on, so for now, set our granularity to one sector.
blkdev_stack_limits() takes care of the rest.

If we decide we cannot support discards,
not only clear the (not user visible) QUEUE_FLAG_DISCARD,
but set both (user visible) discard_granularity and max_discard_sectors
to zero, to avoid confusion with e.g. lsblk -D.

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent edb5e5f6

drivers/block/drbd/drbd_nl.c

+14 −9
Original line number Diff line number Diff line
@@ -1168,21 +1168,20 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi 
	if (b) {

		struct drbd_connection *connection = first_peer_device(device)->connection;



		if (blk_queue_discard(b) &&

		    (connection->cstate < C_CONNECTED || connection->agreed_features & FF_TRIM)) {

			/* For now, don't allow more than one activity log extent worth of data

			 * to be discarded in one go. We may need to rework drbd_al_begin_io()

			 * to allow for even larger discard ranges */

		blk_queue_max_discard_sectors(q, DRBD_MAX_DISCARD_SECTORS);



		if (blk_queue_discard(b) &&

		    (connection->cstate < C_CONNECTED || connection->agreed_features & FF_TRIM)) {

			/* We don't care, stacking below should fix it for the local device.

			 * Whether or not it is a suitable granularity on the remote device

			 * is not our problem, really. If you care, you need to

			 * use devices with similar topology on all peers. */

			q->limits.discard_granularity = 512;

			queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);

			/* REALLY? Is stacking secdiscard "legal"? */

			if (blk_queue_secdiscard(b))

				queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, q);

		} else {

			blk_queue_max_discard_sectors(q, 0);

			queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);

			queue_flag_clear_unlocked(QUEUE_FLAG_SECDISCARD, q);

			q->limits.discard_granularity = 0;

		}



		blk_queue_stack_limits(q, b);
@@ -1194,6 +1193,12 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi 
			q->backing_dev_info.ra_pages = b->backing_dev_info.ra_pages;

		}

	}

	/* To avoid confusion, if this queue does not support discard, clear

	 * max_discard_sectors, which is what lsblk -D reports to the user.  */

	if (!blk_queue_discard(q)) {

		blk_queue_max_discard_sectors(q, 0);

		q->limits.discard_granularity = 0;

	}

}



void drbd_reconsider_max_bio_size(struct drbd_device *device, struct drbd_backing_dev *bdev)

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